U.S. patent application number 15/272408 was filed with the patent office on 2017-03-23 for method of enhancing transmission opportunity and wireless device using the same.
The applicant listed for this patent is MEDIATEK INC.. Invention is credited to Shih-Chang Su.
Application Number | 20170086117 15/272408 |
Document ID | / |
Family ID | 57103806 |
Filed Date | 2017-03-23 |
United States Patent
Application |
20170086117 |
Kind Code |
A1 |
Su; Shih-Chang |
March 23, 2017 |
Method of Enhancing Transmission Opportunity and Wireless Device
Using the Same
Abstract
A method of enhancing a transmission opportunity of a wireless
device comprises sensing a wireless medium; determining an
interframe space duration of the wireless device to be shorter when
the wireless medium is busy; and transmitting a data frame of the
wireless device after the wireless medium is idle for at least the
interframe space duration. By shortening the interframe space
duration, a transmission opportunity of using the wireless medium
is enhanced.
Inventors: |
Su; Shih-Chang; (Hsinchu
County, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MEDIATEK INC. |
Hsin-Chu |
|
TW |
|
|
Family ID: |
57103806 |
Appl. No.: |
15/272408 |
Filed: |
September 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62222217 |
Sep 23, 2015 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 16/14 20130101;
H04W 36/165 20130101; H04W 74/0808 20130101; H04W 84/12
20130101 |
International
Class: |
H04W 36/16 20060101
H04W036/16; H04W 72/04 20060101 H04W072/04 |
Claims
1. A method of enhancing a transmission opportunity of a wireless
device, wherein the wireless device communicates with a second
wireless system and attempts to interoperate with a first wireless
system, and the first wireless system is configured with a first
interframe space duration, the method comprising: sensing a
wireless medium; determining an interframe space duration of the
wireless device to be shorter than a second interframe space
duration specified in a standard corresponding to the second
wireless system when the wireless medium is occupied by the first
wireless system; and p1 transmitting a data frame of the wireless
device after the wireless medium is idle for at least the
interframe space duration, wherein the data frame complies with the
standard corresponding to the second wireless system.
2. The method of claim 1, wherein the step of determining the
interframe space duration of the wireless device when the wireless
medium is busy comprises: determining the interframe space duration
of the wireless device to be the first interframe space duration
when the wireless medium is occupied by the first wireless system;
wherein the first interframe space duration is shorter than the
second interframe space duration.
3. The method of claim 1, wherein the interframe space duration
comprises a short interframe space (SIFS) and a plurality of slot
times.
4. The method of claim 3, wherein the step of determining the
interframe space duration of the wireless device when the wireless
medium is busy comprises: determining the SIFS of the wireless
device to be a first SIFS corresponding to the first wireless
system when the wireless medium is occupied by the first wireless
system.
5. The method of claim 3, wherein the step of determining the
interframe space duration of the wireless device when the wireless
medium is busy comprises: determining the slot time of the wireless
device to be a first slot time corresponding to the first wireless
system when the wireless medium is occupied by the first wireless
system.
6. The method of claim 1, further comprising: determining the
interframe space duration of the wireless device to be equal to the
second interframe space duration when the wireless medium is
occupied by the second wireless system.
7. The method of claim 1, wherein the first wireless system and the
second wireless system are under a distributed coordination
function protocol (DCF), and the interframe space duration, the
first interframe space duration and the second interframe space
duration are a DCF interframe space (DIFS), a first DIFS and a
second DIFS, respectively.
8. The method of claim 1, wherein the first wireless system
operates within a first bandwidth, the second wireless system
operates within a second bandwidth, and the second bandwidth is
narrower than the first bandwidth.
9. The method of claim 1, wherein the first wireless system
complies with one of IEEE 802.11a/b/g/n/ac and the second wireless
system complies with IEEE 802.11j, and the standard is IEEE
802.11j.
10. The method of claim 1, wherein the transmitting step comprises,
transmitting a data frame of the wireless device after the wireless
medium is idle for the interframe space duration plus a backoff
period. cm 11. A wireless device, configured to enhance a
transmission opportunity, wherein the wireless device communicates
with a second wireless system and attempts to interoperate with a
first wireless system, and the first wireless system is configured
with a first interframe space duration, the wireless device
comprising: a processing unit; and a storage unit, coupled to the
processing unit, configured to store a program code, the program
code instructing the processing unit to perform following steps:
sensing a wireless medium; determining an interframe space duration
of the wireless device to be shorter than a second interframe space
duration specified in a standard corresponding to the second
wireless system when the wireless medium is occupied by the first
wireless system; and transmitting a data frame of the wireless
device after the wireless medium is idle for at least the
interframe space duration, wherein the data frame complies with the
standard corresponding to the second wireless system.
12. The wireless device of claim 11, wherein the program code
further instructs the processing unit to determine the interframe
space duration of the wireless device to be the first interframe
space duration when the wireless medium is occupied by the first
wireless system; wherein the first interframe space duration is
shorter than the second interframe space duration.
13. The wireless device of claim 11, wherein the interframe space
duration comprises a short interframe space (SIFS) and a plurality
of slot times.
14. The wireless device of claim 13, wherein the program code
further instructs the processing unit to determine the SIFS of the
wireless device to be a first SIFS corresponding to the first
wireless system when the wireless medium is occupied by the first
wireless system.
15. The wireless device of claim 13, wherein the program code
further instructs the processing unit to determine the slot time of
the wireless device to be a first slot time corresponding to the
first wireless system when the wireless medium is occupied by the
first wireless system.
16. The wireless device of claim 11, wherein the program code
further instructs the processing unit to determine the interframe
space duration of the wireless device to be equal to the second
interframe space duration when the wireless medium is occupied by
the second wireless system.
17. The wireless device of claim 11, wherein the first wireless
system and the second wireless system are under a distributed
coordination function protocol (DCF), and the interframe space
duration, the first interframe space duration and the second
interframe space duration are a DCF interframe space (DIFS), a
first DIFS and a second DIFS, respectively.
18. The wireless device of claim 11, wherein the first wireless
system operates within a first bandwidth, the second wireless
system operates within a second bandwidth, and the second bandwidth
is narrower than the first bandwidth.
19. The method of claim 11, wherein the first wireless system
complies with one of IEEE 802.11a/b/g/n/ac and the second wireless
system complies with IEEE 802.11j, and the standard is IEEE
802.11j.
20. The method of claim 11, wherein the transmitting step
comprises, transmitting a data frame of the wireless device after
the wireless medium is idle for the interframe space duration plus
a backoff period.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application No. 62/222,217, filed on Sep. 23, 2015 and incorporated
herein by reference.
BACKGROUND
[0002] The present invention relates to a method of enhancing
transmission opportunity and a wireless device using the same, and
more particularly, to a method and a wireless device capable of
shortening an interframe space time of the wireless device.
[0003] As a demand for wireless service increases, a bandwidth of
the wireless local area network (WLAN) system is required to be
wider. For example, bandwidths of the WLAN systems complied with
standards of IEEE 802.11a/g are 20 MHz, bandwidths of the WEAN
systems complied with standards of IEEE 802.11n are 20 MHz or 40
MHz, and bandwidths of the WEAN systems complied with standards of
IEEE 802.11ac are 20, 40, 80 MHz or even 160 MHz.
[0004] From another perspective, internet of thing (IoT), which
connects devices through wireless connections, is getting popular
recently. The devices under IoT, expected to provide low data rate
transmission and consume low power, do not require such a wide
operating bandwidth. Typically, a 5 MHz (or 10 MHz) bandwidth is
sufficient for the devices under IoT. In some applications, the
devices under IoT may be narrowband devices, which are originally
configured to operate in a narrowband system (e.g., under a
standard of IEEE 802.11j), and attempt to operate in a wideband
WEAN system (e.g., under a standard of one of IEEE
802.11a/b/g/n/ac). However, the wideband WEAN systems (IEEE
802.11a/b/g/n/ac) are usually not compatible with the narrow WLAN
system (IEEE 802.11j).
[0005] In detail, the narrowband WLAN system and the wideband WLAN
system both perform a distributed coordination function protocol
(DCF) under a carrier sense multiple access with collision
avoidance (CSMA/CA) mechanism. That is, devices under either the
narrowband WLAN system or the wideband WLAN system have to sense a
status of a wireless medium before transmission. If the devices
find that the wireless medium is continuously idle for a specific
duration, i.e., a DCF interframe space (DIFS) duration, the devices
are allowed to transmit data. Otherwise, if the wireless medium is
found busy during the DIFS duration, the devices defer their
transmission. However, the DIFS duration corresponding to the
narrowband WLAN system is much longer than the DIFS duration
corresponding to the wideband WLAN system. In addition, a slot
time, which is related to a length of a contention window of a
backoff mechanism within the CSMA/CA mechanism, corresponding to
the narrowband WLAN system is longer than a slot time corresponding
to the wideband WLAN system as well. Hence, devices under the
narrowband WLAN system would hardly obtain a chance to transmit
data.
[0006] Therefore, how to enhance a transmission opportunity is a
significant objective in the field.
SUMMARY
[0007] It is therefore a primary objective of the present invention
to provide a method of enhancing transmission opportunity and a
wireless device using the same, to improve over disadvantages of
the prior art.
[0008] An embodiment of the present invention discloses a method of
enhancing a transmission opportunity of a wireless device. The
wireless device communicates with a second wireless system and
attempts to interoperate with a first wireless system. The first
wireless system is configured with a first interframe space
duration. The method comprises steps of sensing a wireless medium;
determining an interframe space duration of the wireless device to
be shorter than a second interframe space duration specified in a
standard corresponding to the second wireless system when the
wireless medium is occupied by the first wireless system; and
transmitting a data frame of the wireless device after the wireless
medium is idle for at least the interframe space duration, wherein
the data frame complies with the standard corresponding to the
second wireless system.
[0009] An embodiment of the present invention further discloses a
wireless device, configured to enhance a transmission opportunity.
The wireless device communicates with a second wireless system and
attempts to interoperate with a first wireless system. The first
wireless system is configured with a first interframe space
duration. The wireless device comprises a processing unit; and a
storage unit, coupled to the processing unit, configured to store a
program code, the program code instructing the processing unit to
perform following steps: sensing a wireless medium; determining an
interframe space duration of the wireless device to be shorter than
a second interframe space duration specified in a standard
corresponding to the second wireless system when the wireless
medium is occupied by the first wireless system; and transmitting a
data frame of the wireless device after the wireless medium is idle
for at least the interframe space duration, wherein the data frame
complies with the standard corresponding to the second wireless
system.
[0010] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic diagram of a wireless device according
to an embodiment of the present invention.
[0012] FIG. 2 is a schematic diagram of a process according to an
embodiment of the present invention.
[0013] FIG. 3 is a timing diagram of the wireless device of FIG. 1
accessing a wireless medium according to an embodiment of the
present invention.
DETAILED DESCRIPTION
[0014] Please refer to FIG. 1, which is a schematic diagram of a
wireless device 20 according to an embodiment of the present
invention. The wireless device 20 attempts to interoperate with a
wireless system 10 which complies with a first standard, while the
wireless device 20 is customized for communicating with a wireless
system 22 which complies with a second standard, where the second
standard is different from the first standard. According to the
first standard and the second standard, the wireless system 10
operates within a first bandwidth, and the wireless system 22
operates within a second bandwidth, where the second bandwidth may
be narrower than the first bandwidth. The wireless device 20
comprises a processing unit 202 and a storage unit 204. The storage
unit 204 is coupled to the processing unit 202 and configured to
store a program code 206, where the program code 206 instructs the
processing unit 202 to execute a process for the wireless device 20
to enhance a transmission opportunity during operations of the
wireless system 10. However, according to another embodiment of the
present invention, the wireless device 20 can be two separate
wireless devices wherein one of the two separate devices
communicates with the wireless system 10 with the first standard,
while the other one of the two separate devices communicates with
the wireless system 22 with the second standard. The two separate
wireless devices are located in a neighborhood.
[0015] Notably, even if the first standard and the second standard
are different, both the first standard and the second standard
perform a distributed coordination function protocol (DCF) under a
carrier sense multiple access with collision avoidance (CSMA/CA)
mechanism, which means that the wireless device 20 performs the DCF
under the CSMA/CA mechanism. In other words, the wireless device 20
would wait until a wireless medium is idle for a DCF interframe
space (DIFS) duration plus a backoff period and then perform data
transmission, where the DIFS duration is a short interframe space
(SIFS) duration plus two slot times. Nevertheless, according to the
first standard and the second standard, the wireless system 10 is
configured with a first DIFS duration DIS_1, and the wireless
system 22 is configured with a second DIFS duration DIS_2, where
the second DIFS duration DIS_2 is much longer than the first DIFS
duration DIS_1.
[0016] To be more specific, when the first standard can be IEEE
802.11a, the first DIFS duration DIS_1 is 34 microseconds, which
includes a first SIFS duration SIS_1 specified to be 16
microseconds and a first slot time SLT_1 specified to be 9
microseconds. On the other hand, when the second standard can be
IEEE 802.11j , the second DIFS duration DIS_2 is 106 microseconds,
which includes a second SIFS duration SIS_2 specified to be 64
microseconds and a second slot time SLT_2 specified to be 21
microseconds. Note that, the second slot time SLT_2 is longer than
the first slot time SLT_1 as well.
[0017] If the wireless device 20 simply complies with the second
standard, which means that a DIFS duration DIS_x corresponding to
the wireless device 20 is equal to the second DIFS duration DIS_2,
the wireless system 10 would easily obtain a transmission
opportunity of using the wireless medium to transmit data (since
the first DIFS duration DIS_1 is shorter than the second DIFS
duration DIS_2), such that the wireless device 20 would hardly
obtain a chance to transmit data.
[0018] To enhance a transmission opportunity during operations of
the wireless system 10, the wireless device 20 determines the DIFS
duration DIS_x to be shorter than the second DIFS duration DIS_2.
That is, the wireless device 20 no longer simply complies with the
second standard. Instead, the wireless device 20 shortens the DIFS
duration thereof, compared to the second DIFS duration DIS_2, while
a data frame transmitted from the wireless device 20 remains under
the second standard. In addition, the DIFS duration DIS_x is a SIFS
duration SIS_x of the wireless device 20 plus twice of a slot time
SLT_x of the wireless device 20, i.e., DIS_x=SIS_x+2*SLT_x.
[0019] Please refer to FIG. 2, which is a schematic diagram of a
process according to an embodiment of the present invention. The
process 30 may be compiled as the program code 206 stored in the
storage unit 204 and executed by the processing unit 202. The
process 30 comprises following steps:
[0020] Step 200: Start.
[0021] Step 202: Sense the wireless medium.
[0022] Step 203: Determine whether the wireless medium is busy. If
yes, go to Step 204.
[0023] Step 204: Determine whether the wireless medium is occupied
by the wireless system 10 or occupied by the wireless system 22. If
the wireless medium is occupied by the wireless system 10, go to
Step 206. If the wireless medium is occupied by the wireless system
22, go to Step 208.
[0024] Step 206: Determine the DIFS duration DIS_x corresponding to
the wireless device 20 to be shorter than the second DIFS duration
DIS_2.
[0025] Step 208: Determine the DIFS duration DIS_x corresponding to
the wireless device 20 to be equal to the second DIFS duration
DIS_2.
[0026] Step 210: Transmit a data frame of the wireless device 20
after the wireless medium is idle for at least the DIFS duration
DIS_x, where the data frame complies with the second standard.
[0027] Step 212: End.
[0028] According to the process 20, the wireless device 20 shortens
the DIFS duration DIS_x, which enhances the transmission
opportunity during operations of the wireless system 10.
Specifically, in Step 202, the wireless device 20 senses the
wireless medium to determine whether the wireless medium is idle or
busy (occupied). Details of sensing the wireless medium to
determine whether or not the wireless medium is busy is known by
one skilled in the art, which is not narrated herein for
brevity.
[0029] When the wireless medium is busy, in Step 204, the wireless
device 20 determines whether the wireless medium is occupied by the
wireless system 10 or occupied by the wireless system 22. The
wireless device 20 may try to recognize signals on the wireless
medium. If the wireless device 20 finds that the signals on the
wireless medium is recognizable by the wireless device 20, it
represents that the wireless medium is occupied by the wireless
system 22, since the wireless system 22 complies with the second
standard. Otherwise, if the wireless device 20 finds that the
signals on the wireless medium is not recognizable by the wireless
device 20, it represents that the wireless medium is occupied by
the wireless system 10.
[0030] In Step 206, the wireless device 20 determines the DIFS
duration DIS_x corresponding to the wireless device 20 to be
shorter than the second DIFS duration DIS_2 when the wireless
medium is occupied by the wireless system 10. The wireless medium
occupied by the wireless system 10 represents that the wireless
system 10 already obtains a transmission opportunity of occupying
the wireless medium for transmission. It would be fair to release
some of the transmission opportunity. Hence, the wireless device 20
may gain some of the transmission opportunity of using the wireless
medium by shortening the DIFS duration DIS_x, in comparison to the
second DIFS duration DIS_2. In an embodiment, the wireless device
20 may determine the SIFS duration SIS_x of the wireless device 20
to be the first SIFS duration SIS_1 and the slot time SLT_x of the
wireless device 20 to be the second slot time SLT_2, i.e.,
DIS_x=SIS_1+2*SLT_2, such that the DIFS duration DIS_x is shorter
than the second DIFS duration DIS_2. In an embodiment, the wireless
device 20 may determine the slot time SLT_x of the wireless device
20 to be the first slot time SLT_1 and the SIFS duration SIS_x of
the wireless device 20 to be the second SIFS duration SIS_2, i.e.,
DIS_x=SIS_2+2*SLT_1, such that the DIFS duration DIS_x is shorter
than the second DIFS duration DIS_2. Preferrably, the wireless
device 20 may determine the DIFS duration DIS_x to be equal to the
first DIFS duration DIS_1. In other words, the wireless device 20
may determine the SIFS duration SIS_x of the wireless device 20 to
be the first SIFS duration SIS_1 and the slot time SLT_x of the
wireless device 20 to be the first slot time SLT_1, i.e.,
DIS_x=SIS_1+2*SLT_1=DIS_1, such that the DIFS duration DIS_x is
equal to the first DIFS duration DIS_1 and shorter than the second
DIFS duration DIS_2.
[0031] On the other hand, when the wireless medium is occupied by
the wireless system 22, in Step 208, the wireless device 20
determines the DIFS duration DIS_x corresponding to the wireless
device 20 to be equal to the second DIFS duration DIS_2. The
wireless medium occupied by the wireless system 22 represents that
the wireless system 22 already obtains the transmission opportunity
of occupying the wireless medium for transmission. The wireless
device 20 does not have to be such aggressive to gain the
transmission opportunity of using the wireless medium. Hence, the
wireless device 20 may remain the DIFS duration DIS_x to be equal
to the second DIFS duration DIS_2 as specified in the second
standard.
[0032] In step 210, the wireless device 20 transmits the data frame
after the wireless medium is idle for at least the DIFS duration
DIS_x. The data frame complies with the second standard such that
the data frame is readable/recognized by the wireless system 22. In
addition, the wireless device 20 may enter a backoff mechanism,
i.e., the wireless device 20 may wait for the DIFS duration DIS_x
plus a backoff period BF_x and then perform data transmission after
the backoff period BF_x is due, where the backoff period BF_x is a
random number times the slot time SLT_x, and the slot time SLT_x
may be the second slot time SLT_2 for complying with the second
standard. The backoff mechanism is known by one skilled in the art,
and not narrated herein for brevity. In short, the wireless device
20 transmits the data frame when the wireless medium is idle for at
least the DIFS duration DIS_x.
[0033] Please refer to FIG. 3, which is a timing diagram of the
wireless system 10 and the wireless device 20 accessing the
wireless medium according to embodiments of the present invention.
As shown in FIG. 3, at a time t0, the wireless medium changes from
a busy status to an idle status. A first device within the wireless
system 10 complying with the first standard waits for the first
DIFS duration DIS_1 and may perform data transmission during a
first contention window CW1. Meanwhile, a second device simply
complying with the second standard waits for the second DIFS
duration DIS_2 and may perform data transmission during a second
contention window CW2. Once the first device contends and obtains
the transmission opportunity, the second device is not allowed to
transmit data.
[0034] Notably, the second DIFS duration DIS_2 is even longer than
an average deferring time DT_ave of the first device within the
system 10. The average deferring time DT_ave is the first DIFS
duration DIS_1 plus an average backoff number times the first slot
time SLT_1. The average backoff number may be 7.5 given that a
length of the first contention window CW1 is 15 times the first
slot time SLT_1. Hence, the second DIFS duration DIS_2 (106
microseconds) is longer than the average deferring time DT_ave
(DT_ave=DIS_1+7.5*SLT_1=101.5 microseconds). Therefore, the first
device within the wireless system 10 would be very likely to obtain
the transmission opportunity of using the wireless medium and the
second device simply complying the second standard would hardly
have a chance to transmit data.
[0035] On the other hand, the wireless device 20 determines the
DIFS duration DIS_x corresponding to the wireless device 20 to be
shorter than the second DIFS duration DIS_2, and the wireless
device 20 may perform data transmission during a contention window
CWx. Preferably, the DIFS duration DIS_x may be equal to the first
DIFS duration DIS_1, and thus, the wireless device may have a fair
contention starting point (i.e. , a time t1) with the first device.
Therefore, the wireless device 20 would gain more chances to gain
the transmission opportunity of using the wireless medium, compared
to the second device.
[0036] Notably, the embodiments stated in the above are utilized
for illustrating the concept of the present invention. Those
skilled in the art may make modifications and alternations
accordingly, and not limited herein. For example, the first
standard is not limited to IEEE 802.11a. The first standard may be
one of IEEE 802.11b/g/n/ac, which is within the scope of the
present invention. In addition, in the process 30, the wireless
device 20 determines the DIFS duration DIS_x to be shorter than the
second DIFS duration DIS_2 when the wireless medium is occupied by
the wireless system 10, which is not limited herein. In an
embodiment, the wireless device 20 may determine the DIFS duration
DIS_x to be shorter than the second DIFS duration DIS_2 when the
wireless medium is busy, which is within the scope of the present
invention.
[0037] In addition, details of determining whether the wireless
medium is occupied by the wireless system 10 or occupied by the
wireless system 22 is not limited. In an embodiment, the wireless
device 20 may determine that the wireless medium is occupied by the
wireless system 10 or by the wireless system 22 according to a
physical layer information, where the physical layer information
may be a fast Fourier transform (FFT) related information.
Specifically, when both the wireless system 10 and the wireless
system 22 employ an orthogonal frequency division multiplexing
(OFDM) technique to transmit wireless signals, a subcarrier spacing
corresponding to the wireless system 10 is larger than a subcarrier
spacing corresponding to the wireless system 22, since the first
bandwidth is wider than the second bandwidth. Hence, a fast Fourier
transform period corresponding to the wireless system 10 is shorter
than an FFT period corresponding to the wireless system 22.
Therefore, the FFT period may be used to determine whether the
wireless medium is occupied by the wireless system 10 or by the
wireless system 22.
[0038] In summary, the wireless device determines the interframe
space duration to be shorter than the one specified in the second
standard when the wireless medium is busy, so as to gain more
transmission opportunity to transmit the data frame which complies
with the second standard.
[0039] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *